This invention relates to a beam scanning type electronic copying apparatus for reading out document information by a scanning laser beam and recording the readout document information onto a photosensitive paper.
A conventional beam scanning type electronic copying apparatus scans a document by a laser beam, detects a beam reflected from the document according to the presence and absence of picture elements on the document and reads out the document information by an electrical signal which is photoelectrically converted from the reflected beam. The laser beam is light-modulated according to the readout electrical signal, a photosensitive recording medium is scanned by the modulated laser beam, and the document information is recorded on the photosensitive recording medium. Since such conventional apparatus effects readout of the document information and exposure of the photosensitive recording medium using the same optical system, both the operations can not be simultaneously effected. The readout information obtained by scanning the document by a laser beam is once stored in a buffer memory called "a page memory". When the scanning of one page of the document is completed the document information stored in the page memory is sequentially read out. The laser beam is light-modulated according to the readout information and the photosensitive recording medium is exposed. For this reason, the conventional apparatus is slow in copying speed and requires a large-capacity memory for storing the readout information corresponding to one page of the document, making the apparatus expensive. Where an optical system for document readout and optical system for recording are separately provided, the apparatus becomes bulkier and more expensive.